MAGETWO-57569: [Backport] Functional upgrade test fail 2.1.x --> 2.2.x - 2.2

- Add showing unstable versions during system upgrade test

Author: viktym

dev/tests/functional/tests/app/Magento/Setup/Test/Block/SelectVersion.php

@@ -30,6 +30,13 @@ class SelectVersion extends Form
      */
     protected $firstField = '#selectVersion';
 
+    /**
+     * Show all versions checkbox
+     *
+     * @var string
+     */
+    private $showAllVersions = '#showUnstable';
+
     /**
      * Click on 'Next' button.
      *
@@ -50,9 +57,24 @@ public function clickNext()
     public function fill(FixtureInterface $fixture, SimpleElement $element = null)
     {
         $this->waitForElementVisible($this->firstField);
+        $this->chooseShowAllVersions();
+
         return parent::fill($fixture, $element);
     }
 
+    /**
+     * Show all versions include unstable
+     *
+     * @return void
+     */
+    private function chooseShowAllVersions()
+    {
+        $element = $this->_rootElement->find($this->showAllVersions, Locator::SELECTOR_CSS);
+        if ($element->isVisible()) {
+            $element->click();
+        }
+    }
+
     /**
      * Choose 'yes' for upgrade option called 'Other components'
      *